As deadly wildfires continue across France and Spain experts have said they have been exacerbated by a perfect storm of conditions.

The wildfires have been burning across Europe for ove a fortnight and in Spain three fire have combined close to the capital Madrid with authorities saying the fire is out of control due to its scale and ferocity.

Spain’s prime minister Pedro Sánchez warned the country faced “a dramatic situation,” after the country decision to declare a state of national emergency

Dr Francesca Di Giuseppe, fire forecast coordinator, at the European Centre for Medium Range Weather Forecasts (ECMWF), said a hydroclimatic rebound has added to the risks.

“From a hydroclimatic perspective, the fires in Spain reflect a sequence of conditions developing over several months, not only the extreme weather of recent days,” he explained. “A relatively wet spring promoted vegetation growth and increased the amount of potentially burnable material; this was followed by persistent heat, limited rainfall and low humidity, which rapidly dried soils and vegetation.

“This transition from wet, vegetation-favouring conditions to intense summer drying has created an hydroclimatic ‘rebound’, with abundant and highly flammable fuels. Combined with very high temperatures, exceptionally low humidity and strong winds, these conditions allow any ignition to spread rapidly and make suppression particularly difficult.”

Víctor Resco de Dios, lecturer of Forestry Engineering and Global Change, at the University of Lleida and researcher at Agrotecnio, said: “The intensity of fire seasons has increased by an average of 30–40 per cent over recent decades. We have been warning about this for many years. This increase in intensity is due to all the energy stored in the countryside in the form of biomass, as a result of rural depopulation and, at times, excessively protectionist environmental policies. It is also, on the other hand, because the atmosphere is laden with drying energy, as a consequence of the burning of fossil fuels.”

He continued: “What matters is not the type of vegetation, but the type of fuel – that is, how much biomass there is and, above all, how it is spatially connected. That is why we talk about creating mosaic landscapes, where discontinuities are introduced into the landscape: areas where the intensity of the flames decreases and firefighters can extinguish the fires. It is often claimed that pine and eucalyptus trees are to blame for the fires. The reality is that 70 per cent of what burns is scrubland and that the area of pine forest affected is decreasing (fires in eucalyptus plantations have always been rare, as they cover a very small area). On the contrary, studies show that protected areas are burning more frequently, precisely because of this continuity in vegetation and biomass (which does not mean that protected areas are a bad thing, but rather that fuel and fire must be managed).”

“The ferocity of the fires affecting Toledo, Madrid and Ávila is due to a combination of factors, notably two consecutive years of heavy rainfall followed by a sudden halt in the rains in May and the immediate onset of summer with consistently high temperatures and low humidity,” added Eduardo Rojas Briales,l at the Polytechnic University of Valencia and former Deputy Director-General of the FAO. “Added to this is the fact that this is the part of the Central Mountain Range with the lowest rainfall, due to the lower altitude of its highest peaks, and consequently, vegetation that is more xerophytic and prone to burning than in other areas of the Central Mountain Range.

“Compounding this is a northward shift in recent years of the contra-trade winds (a dry, warm tropical wind from the south-west), which sweep across the land in elevated areas south of the temperate storm cycle and are well known in Tenerife and La Palma for causing fires in the highest pine forests. Finally, the intense pressure from the Madrid property market, combined with the quality of these landscapes, has led to a great deal of scattered development—some of which predates modern town-planning regulations—and which poses many risks and diverts resources.”

Juli G. Pausas, CSIC lecturer at CIDE (Centre for Research on Desertification), Valencia, said: “This is the chronicle of a situation long foretold. Once we, as a society, have accepted that we are changing the climate, these fires become part of the new normal; in other words, they are exactly what we expected. For decades, it has been warned that if we continue to drive up temperatures, the consequences could be very serious, including a significant increase in the frequency, size and intensity of wildfires. With the temperatures and heatwaves, we are currently experiencing, almost any type of vegetation can catch fire. Last summer we saw beech forests go up in flames, something unexpected.

“From an ecological point of view, it is worth remembering that many of the areas affected by fires, especially those with a Mediterranean climate, will recover and biodiversity will not be lost. The situation is more problematic in the case of fires affecting higher-altitude areas, where species are not as well adapted to fire, as is the case with the beech trees I have just mentioned.

“The solutions, of course, are not straightforward, and include both tackling climate change aggressively to prevent it from getting worse,  and implementing fire prevention measures better suited to the new climate.”